A multi-organizational quality improvement collaborative is a proven strategy for implementing organizational change. Failure to sustain improvements is a direct waste of invested resources, has costs associated with missed opportunities, and may affect an organization's ability to implement change in the future. Research on the effectiveness of quality improvement collaborative to promote long-term sustainment of change is lacking, however. Moreover, we do not yet understand what attributes--organizational, innovation or environmental-are the most important contributors to the ability of organizations to successfully sustain change following participation in quality improvement collaborative. This application is the next logical step for our research program, and explores the sustainment of organizational change in substance abuse clinics after their participation in the NIATx200 initiative - a quality improvement collaborative designed to test the effectiveness of four different implementation strategies to improve access to and retention in treatment. In this study, we will seek to answer a fundamental research question: Are changes implemented using the NIATx implementation strategy sustainable? Using longitudinal administrative data and key informant interviews, we will explore whether improvements experienced by NIATx200 clinics located in Michigan, New York and Washington were sustained following participation in a quality improvement collaborative, and to identify the environmental, organizational and innovation-related factors that influenced sustained improvements. Our research team has extensive expertise in performing quality improvement and research in addiction treatment, sustainability and state policy, and qualitative research. The findings will contribute to implementation research by exploring sustainment of change after participation in a quality improvement collaborative and by providing a broader understanding of sustainability of organizational change within substance abuse clinics. The current project represents a foundational step in the field of implementation research by enabling researchers and practitioners to improve quality improvement collaborative to enhance sustainability of change.